Re: 440 - Eddy 750 - Stumble but AND LEAN LIKE THE REST
[Re: Steve Bryant]
#1611409
04/30/14 10:46 AM
04/30/14 10:46 AM
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Joined: Aug 2013
Posts: 518 Georgia
Steve Bryant
OP
mopar
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OP
mopar
Joined: Aug 2013
Posts: 518
Georgia
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Rod is replaced, storms gave me a break and so I drove about 30 miles yesterday with with some tuning changes and have an update.
As it turns out, I have the same lean condition everyone else has. It appeared intermittently only in first gear and is more predominant with an incline and under a load. My rear drums don't help since they take a second to release.
Secondly, I am lean in cruise mode running between 13.1-14. Lastly, I have determined that I like the metering springs to move SLIGHTLY above cruise so I have nailed down the mid-top settings. Here is my carb changes:
1) Moved the accelerator rod to the top hole. This gives the carb more fuel off-idle and NEARLY solved the lean condition out of first. 2) For now, the Primaries as still Stock 1432 (.110) 3) During power situations (before WOT) I was still running lean (16+) so I changed the secondaries two steps larger - 1433 (.113) 4) To keep the primaries the same and provide even more fuel to the secondaries I moved to Rods - 1458 (75/37) Stock Primary, Richer Secondary 5) With the stock springs I REALLY had to stomp on it to get the A/F to drop down into the 12.5-13 POWER mixture so I change the springs to the Pink 7-in HG
The results are as follows:
Idle: is still in the low 13's. I simply cannot adjust it any leaner without sacrificing too much Vacuum. I am OK with this number. Off-Idle: May still give me an intermittent lean surge but I will test further and test various pump nozzles. You can see it on the A/F gauge. As you ease out the clutch and give it some gas, the A/F will drop a point as the pump is starting to load and then the A/F will shoot up to about 16 (lean) and then the engine will stumble. More throttle enriches the mixture and all is good. This takes about a second. Cruise: is a TAD rich. I average about 13.8 depending on load and Vacuum. I am considering moving to a smaller primary jet today to see if I can do something about this. I expect to have to overcompensate the Accelerator Pump if I do this. Off-Cruise: (slight power) gets me into the 14.1-14.9 range which has a good feel. Power : So I like the power to kick in before I put the pedal to the floor so I moved to the pink spring. During passing or a more aggressive pedal push the mixture MAY get to 15.5 then it will drop down to around 13 and you can feel the car liking that extra fuel. WOT : This is really no different than power. Since I moved to a 7 GB spring, the metering opens up at a higher vacuum (lower RPM)so I get power without having to floor it.
I am no carb expert at ALL, but I can tell you that these easy adjustments fit well with the way I spec'ed the engine. I was looking for the HP and torque to come in the 1000-2500 RPM range and so these tweaks with the carb are providing the mixture I need with the cam and intake manifold I chose. Every transition is smooth and without surges or drops in A/F. I will have to make a movie of the transitions so you can see the ups and downs. I need to lean out the low end a little more and then this car will be dialed in.
With the 440 and RPM Intake my 1411 is giving me a slightly rich idle, a fairly consistent off-idle (working on it) a slightly rich cruise (working on it) and a fantastic power circuit.
Today I am going to work on the pump mixture, lean out the cruise and report back. I have a feeling that by leaning out the primaries I will make the lean stumble more predominant but we will see. I really don't want to cruise in full power nor do I want to cruise with a rich mixture.
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Re: 440 - Eddy 750 - Stumble but AND LEAN LIKE THE REST
[Re: Steve Bryant]
#1611412
04/30/14 02:06 PM
04/30/14 02:06 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I forgot what numbers we were shootin for (I gotta head out the door ASAP) but the jet will change cruise and power and a rod with a different cruise (same power) will only change the cruise
live every 24 hour block of time like it's your last day on earth
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Re: 440 - Eddy 750 - Stumble but AND LEAN LIKE THE REST
[Re: Cab_Burge]
#1611416
04/30/14 11:00 PM
04/30/14 11:00 PM
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Joined: Jan 2003
Posts: 3,967 S.I. N.Y.
1MYTGTX
master
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master
Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
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Following this thread as I just installed an 800 Thunder on my 440. Right out of the box I had much better throttle response over my 750 vac sec Holley. I am not experiencing any off idle stumbles at all. Only thing I am battling is a "dirty" idle. Has the same eye watering, clothes stinking smell as my Holley did. Only installed it Monday & really didnt do any tuning to it except try & play with mixture screws (didnt really help) Looking forward to more of your updates!
1MYTGTX
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Re: 440 - Eddy 750 - Done. I am happy with result
[Re: Steve Bryant]
#1611426
05/05/14 09:54 PM
05/05/14 09:54 PM
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Joined: Aug 2013
Posts: 518 Georgia
Steve Bryant
OP
mopar
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OP
mopar
Joined: Aug 2013
Posts: 518
Georgia
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OK, I have two updates:
1) I determined that I did not have the correct plate between my carb and the intake. Performer and RPM manifolds require a cover or gasket that covers and seals the additional carb holes on the intake manifold. Part #9266 or #2732. I bought #9266 to help dissipate some of the heat and I noticed far more consistent vacuum at idle and cruise. The A/F doesn't bounce around anymore. 2) A buddy loaned me his AVS 800 and I am sold. Others have said it, Edelbrock recommends it and I am amazed at the difference everyone told me I would see. As soon as I adjusted the idle mixture and speed it cranked up and I would swear I have a different car.
You guys know that I wanted the 1411 to work and it does. I eliminated the lean stumble, I have a mixture that feels great and the numbers look good on the A/F. Having said that, let me try to explain the difference in raw facts.
1) With the 800, releasing the clutch in 1st gear is like any other car. You just release the clutch, period. No feathering and slipping the clutch. It just works, no matter the load no matter the incline. 2) With the 800, the mixture defaulted to perfect. Cruise is pretty solid around 14.2 and when you punch it you get an INSTANT drop down to roughly 11. As RPMs incrase the A/F increases to roughly 15.0 and then the vacuum kicks in and it drops back down into power mode.
For the most part, I think it has to do with the accelerator pump. When there is a load low in gears and at a start, the A/F is down in the 11.5-12.5 range. There are absolutely no lean spikes anywhere in the RPM range. When I replaced the pump nozzle to a 43, it eliminated the stumble but I still noticed quick lean spikes shifting gears or from a start. The nozzle have a good healthy squirt of fuel but as RPM's increased, the transition would still have a quick little spike that you couldn't really feel but it showed up in the gauge.
Nothing like that with the 800. It is smooth, responsive and a night-and-day difference.
Amazing is the only word that comes to mind.
I am a lot smarter now than I would have been if I had bought the 800 first so I have no regrets but I will say that the 800 is cheaper than a 750 with a tuning kit and nozzle kit.
I will respond back with any comments, questions that may arise but I will say that I HAVE SEEN THE LIGHT.
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